It is known that cold, wet weather can be dangerous to an over-heated horse following hard work or a demanding performance. Covering the hind quarters with a cover prevents chilling and allows the heavy muscles to cool out slowly, helping to prevent muscle cramps and spasms.
A current, commercially available horse cover, such as the Swedish Hansbo Rug, which works as an under blanket, or traveling rug, has two distinct layers. The inner layer of polyester, wicks moisture away from the horse to the outer layer of cotton, where it evaporates. The Hansbo Rug is not adaptable to be used as a hind quarter cover while riding. It is better utilized as a cover for a horse which is inactive and not for short or long distance riding. Furthermore, the wicking and evaporation of moisture would cool the rug and chill the horse.
Another available back pad is made from wool with a half inch poly-felt fill and is designed to absorb perspiration. The back pad is designed primarily as a saddle blanket and not to protect the horse's hind quarters.
U.S. Pat. No. 688,203 discloses a harness shield attachment which is designed to be adjusted over the haunch of an animal and underneath the tail to hold a guard in place by buttons or other fastening devices on the harness and a securing attachment for the tail. The device is designed primarily to protect the harness from becoming fouled. The shield attachment would not provide weather protection for the horse nor could it be conveniently rolled up or folded away.
I have found however, that new, state-of-the-art materials used in other applications and properly designed are available to overcome the disadvantages of the prior art horse covers.